Grilles of various types and various forms of construction are widely used as sunshades, decorative facings, such as on walls and ceilings, and as vision barriers, both interior and exterior. There are many types of construction used in such grilles which permit the components of the grilles to be fabricated and shipped to the site of use in parts with little labor being required at the site to assemble and erect the grille. It is, of course, desirable that the structure of the components of the grille be such that they can be nested for shipping, particularly when the components are shipped over long distances, thereby to conserve space and save in shipping costs. It is similarly desirable that such grilles be easy to assemble and erect, thus to keep on site costs low.
One form of grille that has been marketed heretofore is composed of one-piece circular elements, each of which has on the outside of the walls diametrically opposite outwardly extending male and female matching dovetail flanges that extend parallel to the axis of the circular walls of the element, the dovetail flanges being located 90.degree. apart around the periphery of the element. That form of grille is assembled by sliding each element axially along adjacent elements to join the dovetails and then peening or otherwise upsetting material at the ends of the dovetails to anchor the dovetail connections against sliding lengthwise.
A significant disadvantage of the grille just described is that the parts cannot be nested for shipment, thus adding considerably to the installed cost of the grille when there is a considerable distance between the place of manufacture and the place of installation. Moreover, it is desirable that the male (tenon) and female (mortise) parts of the dovetail connections between the elements fit closely while still permitting the elements to be slided together to connect them, and to the extent that the tolerances of the dovetails are established to provide a good fit, the more difficult is the operation of sliding them into place upon assembly. On the other hand, the establishment of tolerances that make the dovetails easy to slide together makes the fit between the parts of the dovetail poorer and the connection between elements less durable.